1. Field of the Invention
The present invention relates a curved guide mechanism which guides a movable body along an arcuate guide track, and a walk-assisting device using this guide mechanism.
2. Description of the Related Art
In the related art, as this type of walk-assisting device, one including a seating member on which a user sits down in a straddling posture and a leg link supporting the seating member from below, and adapted to receive at least a portion of user's weight via the seating member by a leg link, thereby reducing a load acting on the user's leg to assist in his or her walking is known (for example, refer to Japanese Patent Application Laid-Open No. 2007-20909).
In this walk-assisting device, the seating member and the leg link are connected together via a curved guide mechanism composed of a guide unit and a movable body. The guide unit has an arcuate guide track and is connected to the seating member. The arcuate guide track has a center of curvature located above the seating member and is long in a front-back direction. The movable body is fixed to the leg link and is movably engaged with the guide track via a plurality of engagement elements comprised of rotating bodies. Therefore, the leg link is rockable in the front-back directions with the center of curvature of an arcuate shape which is the shape of the guide track as a rocking fulcrum. According to this configuration, in a case where a point of action of the weight of user's upper body relative to the seating member deviates forward of a rocking fulcrum in the front-back directions of the leg link, and the seating member inclines forward and downward, the rocking fulcrum in the front-back directions of the leg link is located above the seating member. Therefore, the weight acting point is shifted rearward below the rocking fulcrum in the front-back directions of the leg link, the distance in the front-back directions between this fulcrum and the weight acting point decreases, and a rotation moment which acts on the seating member also decreases. Also, the rotation moment which acts on the seating member becomes zero in a place where the weight acting point has been shifted to a position just below the rocking fulcrum in the front-back directions of the leg link, and the seating member is stabilized in this state. Thus, since the seating member automatically converges into a stable state thereof, the seating member can be kept from deviating in the front-back directions below a user's hip.
Here, in the above related-art example, an arcuate rail used as a guide track is fixed to the guide unit, and an inner engagement element and an outer engagement element which are rotatably engaged with an inner peripheral side edge (upper edge) near the center of curvature of the arcuate shape and an outer peripheral rail side edge (lower edge) distant from the center of curvature are provided at front and rear ends, respectively, of the movable body. Therefore, the width of the movable body in an up-down direction becomes a dimension obtained by adding the diameter of the inner engagement element and the outer engagement element to the width of the rail in the up-down direction. As a result, there is a problem such that the movable body becomes large and heavy, and the inertia moment of the leg link increases. Additionally, foreign matters, such as trousers, unfavorably enter into a space between a side edge of the rail and an engagement element engaged therewith to be squeezed in the space, and the smoothness of rocking motion of the leg link might be impaired.